Field of the Invention
The present invention relates to a glow plug.
Description of Related Art
A glow plug is used as an auxiliary heat source of a compression ignition internal combustion engine (for example, a diesel engine or the like). As a glow plug, a glow plug is known which is provided with an additional function to measure a pressure within a combustion chamber by a pressure sensor provided (for example, Patent Document 1). The pressure sensor measures a change in pressure within the combustion chamber by making use of the movement of a heater portion which projects into the combustion chamber. The movement is generated in association with a change in pressure and occurs along the direction of an axis of the heater portion. When the heater portion moves in this way, it is preferable that gas-tightness is ensured between the glow plug and the combustion chamber while holding the heater portion movable. To make this happen, the glow plug includes a thin sheet-like membrane portion (in general, also, referred to as a “membrane”). The membrane portion connects the heater portion and a housing together.